Final answer:
A scatterplot displays a cluster when a group of data points is concentrated in a specific area on the plot, indicating a correlation between the variables.
Step-by-step explanation:
A scatterplot displays a cluster when a group of data points is concentrated in a specific area on the plot. The cluster can be seen as a tight grouping of points. For example, if we have a scatterplot showing the number of hours studied and the test scores of a group of students, and we notice a cluster of points in the top right corner of the plot, it indicates that students who studied a lot scored highly on the test.
This cluster can be interpreted as a positive correlation between the number of hours studied and test scores. The closer the points are to each other within the cluster, the stronger the correlation. In this case, we can conclude that studying more hours generally leads to higher test scores.